A Frequency Control Method by Wind Turbine Generator/Battery using Load Estimation in Isolated Power System

Abstract

This paper presents a frequency control method by a coordinated control of a wind turbine generator (WTG) and a battery energy storage system (BESS) using load estimation in an isolated power system. The load variation is assumed as a disturbance to the power system and can be estimated by using a disturbance observer. For the load estimation, H_∞ control theory and parameter identification are applied to achieve robust control performance. Each output power command of the WTG and the BESS is determined by using the estimated load. Low frequency component in the load variation is reduced by the WTG with pitch angle control, while high frequency component in the load variation is reduced by the BESS with charge/discharge operation, respectively. In addition to the frequency control, a capacity reduction technique for BESS is proposed. The effectiveness of the proposed method is verified by numerical simulations.